In recent years, in relatively small-scale areas such as office buildings, industrial facilities, and the like, electrical power generators are driven by using drive sources which use gas, oil, or the like, as a fuel, and there is a trend to use systems that self-contained electrical energy. In particular, as a drive source for an electrical power generator, the technology used in small-scale gas turbines that are driven using low cost fuel and have a low noise level has been progressing, its flexibility has been increasing, and thus there is a trend to expand the use of these.
There are many cases in which self-contained electrical power systems such as these have an exhaust heat recovery system attached in which exhaust heat generated by the drive source when driving an electrical power generator is recovered, and is used for supplying hot water and air conditioning within the area.
FIG. 13 shows an example of an exhaust heat recovery system. In FIG. 13, reference numeral 501 is a gas turbine, 502 is a heat exchanger for exhaust heat recovery, 503 is a hot water storage tank, 504 is a hot water supply column, 505 is a water supply tank, 506 is a heat exchanger for hot water supply temperature adjustment, and 507 is a cooling tower. The gas turbine 501 and the heat exchanger 502 for exhaust heat recovery are connected by an exhaust gas feed pipe 508, and furthermore, an exhaust tower 509, which discharges the exhaust gas that has heated water, is provided in the heat exchanger 502 for exhaust heat recovery.
The heat exchanger 502 for exhaust heat recovery and the hot water storage tank 503 are connected by a primary pipe 510 that forms a closed cycle system in which the water (hot water) is circulated. In addition, the storage tank 503, the hot water supply column 504, and the heat exchanger 506 for hot water supply temperature adjustment are connected by a secondary pipe 511 that forms a closed cycle system in which hot water is circulated. The water supply tank 505 is connected to the secondary pipe 511 by a water supply pipe 512. Furthermore, the heat exchanger 506 for hot water supply temperature adjustment and the cooling tower 507 are connected by a coolant pipe 513 that forms a closed cycle system in which water is circulated as a coolant.
In the exhaust heat recovery system described above, the exhaust heat of the gas turbine 501 is fed into the heat exchanger 502 for exhaust heat recovery, then is discharged to the hot water storage tank 503, then heat exchange with the water circulating in the primary pipe 510 is carried out, and thereby the water is heated. The water (hot water) heated in the heat exchanger 502 for exhaust heat recovery flows into the hot water storage tank 503. The water (hot water) from the hot water storage tank 503 is circulated in the secondary pipe 511, and when the hot water supply column 504 is opened, the water flows outside the system and is used. When the remaining amount of water (hot water) in the hot water storage tank 503 becomes small, an appropriate amount of water is supplied from the water supply tank 505.
In addition, in the exhaust heat recovery system described above, when the use of water (hot water) that circulates through the secondary pipes 511 is low, the temperature of water (hot water) in the system rises excessively. Thus, in this case, in the heat exchanger 506 for hot water supply temperature adjustment, excess heat energy is recovered and discharged into the atmosphere by the cooling tower 507.
In the exhaust heat recovery system described above, there are problems in that the cooling facility formed by the heat exchanger 506 for hot water supply temperature adjustment and the cooling tower 507 are necessary, and thereby the system as a whole becomes complicated and large, and the costs for the installation easily increase.
In addition, accompanying the expansion of use of the self-contained type power supply systems, exhaust heat recovery systems having high energy efficiency are required.